Etiology

Cytomegalovirus is a DNA virus belonging to the herpesviruses group, and is also known as Human Herpesvirus 5 (HHV-5). It is found in all geographic locations and socioeconomic groups, and infects between 50-80% of adults in the United States as indicated by the presence of antibodies in much of the general population.

Radiographic features

Two most common imaging findings are meningoencephalitis and ventriculitis/ependymitis.

MRI

In CMV encephalitis, there is usually only non specific increased T2/FLAIR signal in the white matter. If ventriculitis is also present then enhancement of the ependymal surface and hydrocephalus may also be seen.

high T2 white matter change most prominent in a periventricular distribution

no enhancement (unless ventriculitis present, in which case 30% or so will enhance)

no mass effect (often seen with concurrent atrophy)

Appearances are similar to HIV encephalitis, although usually CMV occurs in patients with a longer duration of disease, and lower CD4+ counts.